The focus of this dissertation was to study the experiences and perceptions of four teachers involved in the implementation and the sustaining of the National Math and Science Initiative. The National Math and Science Initiative (NMSI) is a program funded by the private sector, with some financial backing from various divisions of the federal government. This reform was developed, in part, to respond to the United States of America’s STEM (Science, Technology, Engineering, and Mathematics) crisis in the U.S. (National Math and Science Initiative, 2013). The National Math and Science Initiative (NMSI) is an aggressive reform that serves to raise interest in these areas by providing schools with resources, training, and methods for restructuring. The goal is to put more students, especially those of underrepresented populations, in Advanced Placement classrooms. The NMSI reform provides guidance, financial support, and training for teachers and students for three years. This phenomenological study focused on the experiences of four teachers responsible for implementing the reform. The purpose of this study was to investigate 1) the experiences teachers had in implementing the NMSI reform, 2) what factors contributed to implementation, and 3) to what degree the reform was sustained after the initial three-year onboarding. Themes, implications for future research, and recommendations are presented. The findings in this study address the impact the National Math and Science Initiative can have on the teaching and learning climate of an institution and may serve as a foundation for future studies.